The global economy depends upon the physical shipment of materials between markets. The scale and pace at which these materials are shipped has exploded in recent years due in part to the invention and proliferation of the intermodal container. Ninety percent of the world's freight now moves in a container. Virtually anyone in the world can arrange with an international shipper or carrier to have an empty intermodal container delivered to their home or workplace. They then could load it with tons of material, declare in only the most general terms what the contents were, “seal” it with a 50-cent lead tag, and send it on its way to any city and town in the United States. The job of transportation providers was to move the box as expeditiously as possible and to exercise care to ensure that the integrity of a container's contents was not compromised.
The responsibility for making sure that goods loaded in a container were legitimate and authorized is shouldered almost exclusively by the importing jurisdiction. However, as the volume of containerized cargo has grown, the number of agents assigned to police that cargo has stayed relatively flat or even declined among most trading nations. The rule of thumb in the inspection business is that it takes five agents three hours to conduct a thorough physical examination of a single full intermodal container. Last year nearly 20 million containers were delivered to America's borders via ship, train, and truck. Approximately 1 to 2 percent of that cargo was actually inspected.
Thus, for would-be terrorists, the global intermodal container system that is responsible for moving the overwhelming majority of the world's freight provides ample opportunity for launching a terrorist attack. The almost complete absence of any security oversight in the loading and transporting of a container from its point of origin to its final destination and the growing volume and velocity at which containers move around the planet creates a daunting problem for inspectors. The use of these containers as a weapon has the potential to halt all shipments of containerized cargo into our ports and across our borders. Consequently, a relatively low cost terrorist attack could result in billions of dollars in losses to the U.S. economy.
Given the current state of container security, it is hard to imagine how a post-event lockdown on container shipments could be either prevented or short-lived. A terrorist could easily use a container as a weapon delivery device, for example, high-explosives such as those used in the attack on the Murrah Federal Building in Oklahoma City, some form of chemical weapon, a bio weapon, a nuclear device or “dirty bomb.” All these scenarios are conceivable since the choice of a weapon would not be constrained by any security measures currently in place in seaports or within the intermodal transportation industry.
Conventional devices for inspecting containers generally involve the use of penetrating radiation to detect contraband. For example, U.S. Pat. No. 4,430,568 (Osami Yoshida et al.) describes a package inspection system for automatically inspecting the contents of a package, such as a container, unloaded from a ship without opening or unpacking the container. The device comprises an X-ray transmitter, an X-ray receiver, and a processing unit for image processing. This device relies on a large X-ray unit and requires the container be moved through the unit. Similarly, U.S. Pat. No. 5,638,420 (Armistead) describes a radiographic inspection apparatus for large containers, vehicles and structures having a movable frame, which can straddle the container or object being inspected. The straddling frame has opposed parallel sides, which carry a source of penetrating radiation and a detector array. The source or sources are moved along the length of a container while radiographic image data is being sequentially recorded. While this device does not necessarily require the movement of the container to an inspection site, the straddling frame at least requires some space between containers in which to move. Since containers are often stacked in close proximity, the Armistead device would at least require that some containers be moved prior to inspection. Furthermore, neither of the devices described above provide for the actual detection of chemical or biological contaminants, rather they rely on radiation imaging to detect suspect structures or nuclear materials.
Published U.S. Patent Application No. 2003/0201394 (Peoples) describes a device that detects radiological or chemical contaminants in cargo containers via a detector system mounted upon a spreader bar. The device is capable of sampling air next to an existing opening, such as a vent, in the container or inserting an air sampling probe into a spring loaded door located in the roof of the container. The device described by Peoples centers on the rationale that the container being inspected is in the process of being lifted by the spreader bar and is not in close proximity to other containers. Therefore, any contamination detected in the air adjacent to the container is assumed to emanate from the container being lifted. This device would not provide accurate results if the container were in storage and stacked adjacent to other containers. In addition, the spring loaded door requires the modification of the existing container.
Published U.S. Patent Application No. 2004/0024278 (Megerle) describes a device that samples the air of a container for biological and chemical contaminants. The device is directed toward containers having an air distribution plenum that can establish a flow of air through the container, which is then analyzed for the presence of hazardous materials. Similar to the device described in Peoples, this device also requires the modification of the container by installing a means to distribute an air flow through the container. In addition, the Megerle device requires both an air delivery mechanism and an air collection mechanism since the system relies upon a positive pressure source for its air supply.